Palladium-Ceria Catalysts with Enhanced Alkaline Hydrogen Oxidation Activity for Anion Exchange Membrane Fuel Cells
Palladium-Ceria Catalysts with Enhanced Alkaline Hydrogen Oxidation Activity for Anion Exchange Membrane Fuel Cells
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DOI：
10.1021/acsaem.9b00657
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发表时间：
2019-07-01
影响因子：
6.4
通讯作者：
Vizza, Francesco
中科院分区：
文献类型：
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作者：
Bellini, Marco;Pagliaro, Maria V.;Vizza, Francesco
与质子交换膜燃料电池相比，阴离子交换膜燃料电池 (AEMFC) 具有几个重要优势，包括可以避免使用铂催化剂，从而帮助克服燃料电池系统的高成本。尽管有这些潜在的好处，但碱性介质中氢氧化反应 (HOR) 的缓慢动力学和性能稳定性的限制（由于阴离子导电聚合物电解质成分的降解）通常阻碍了 AEMFC 的发展。用活性但更可持续的 HOR 催化剂代替 Pt 是一个关键目标。在此，我们报道了通过设计 Pd-CeO2 界面接触合成 Pd-CeO2/C 催化剂。优化的 Pd-CeO2 界面接触可提高 HOR 活性，从而在 AEMFC 测试中实现 >1.4 W cm(-2) 峰值功率密度。这是迄今为止报道的唯一与最先进的 AEMFC 功率性能 (>1 W cm(-2)) 相匹配的无 Pt HOR 催化剂。密度泛函理论计算表明，异常的 HOR 活性可归因于 Pd 原子与 CeO2 氧原子的相互作用削弱了氢结合能。 X 射线吸收光谱证实，这种相互作用是由由四个 CeO2 氧原子配位的氧化 Pd 原子组成的结构促进的。
Anion exchange membrane fuel cells (AEMFCs) offer several important advantages with respect to proton exchange membrane fuel cells, including the possibility of avoiding the use of platinum catalysts to help overcome the high cost of fuel cell systems. Despite such potential benefits, the slow kinetics of the hydrogen oxidation reaction (HOR) in alkaline media and limitations in performance stability (because of the degradation of the anion conducting polymer electrolyte components) have generally impeded AEMFC development. Replacing Pt with an active but more sustainable HOR catalyst is a key objective. Herein, we report the synthesis of a Pd-CeO2/C catalyst with engineered Pd-to-CeO2 interfacial contact. The optimized Pd-CeO2 interfacial contact affords an increased HOR activity leading to >1.4 W cm(-2) peak power densities in AEMFC tests. This is the only Pt-free HOR catalyst yet reported that matches state-of-the-art AEMFC power performances (>1 W cm(-2)). Density functional theory calculations suggest that the exceptional HOR activity is attributable to a weakening of the hydrogen binding energy through the interaction of Pd atoms with the oxygen atoms of CeO2. This interaction is facilitated by a structure that consists of oxidized Pd atoms coordinated by four CeO2 oxygen atoms, confirmed by X-ray absorption spectroscopy.